Based on kernel version 2.6.26. Page generated on 2008-07-16 21:13 EST.
1 2 SMP IRQ affinity, started by Ingo Molnar <mingo[AT]redhat[DOT]com> 3 4 5 /proc/irq/IRQ#/smp_affinity specifies which target CPUs are permitted 6 for a given IRQ source. It's a bitmask of allowed CPUs. It's not allowed 7 to turn off all CPUs, and if an IRQ controller does not support IRQ 8 affinity then the value will not change from the default 0xffffffff. 9 10 Here is an example of restricting IRQ44 (eth1) to CPU0-3 then restricting 11 the IRQ to CPU4-7 (this is an 8-CPU SMP box): 12 13 [root@moon 44]# cat smp_affinity 14 ffffffff 15 [root@moon 44]# echo 0f > smp_affinity 16 [root@moon 44]# cat smp_affinity 17 0000000f 18 [root@moon 44]# ping -f h 19 PING hell (195.4.7.3): 56 data bytes 20 ... 21 --- hell ping statistics --- 22 6029 packets transmitted, 6027 packets received, 0% packet loss 23 round-trip min/avg/max = 0.1/0.1/0.4 ms 24 [root@moon 44]# cat /proc/interrupts | grep 44: 25 44: 0 1785 1785 1783 1783 1 26 1 0 IO-APIC-level eth1 27 [root@moon 44]# echo f0 > smp_affinity 28 [root@moon 44]# ping -f h 29 PING hell (195.4.7.3): 56 data bytes 30 .. 31 --- hell ping statistics --- 32 2779 packets transmitted, 2777 packets received, 0% packet loss 33 round-trip min/avg/max = 0.1/0.5/585.4 ms 34 [root@moon 44]# cat /proc/interrupts | grep 44: 35 44: 1068 1785 1785 1784 1784 1069 1070 1069 IO-APIC-level eth1 36 [root@moon 44]#
